If a 12 sided regular polygon rotates about its center at which angle of rotation will the image of the polygon coinside with the prelim age

30 degrees

This is the minimum amount of rotation.

Why this value? Well because 360/12 = 30

Consider a triangle with 3 sides. Specifically I mean an equilateral triangle. We can rotate it 120 degrees to have it line up with itself. Now notice that 360/3 = 120.

For a square, we can rotate it 90 degrees and we can say 360/4 = 90

So the general rule is that the minimum angle of rotation is 360/n, where n is the number of sides. This rule only works for regular polygons. Regular polygons have the same side length and the same angle measure (the side and angle measure won't necessarily be equal).

So going back to this 12 sided dodecagon, we have n = 12 and 360/n = 360/12 = 30 as the minimum angle of rotation. Each 30 degree rotation will have the polygon match up perfectly with its old image. The preimage and image will be identical.

0.02040816326